FPGA VAX update, now DIY TTL computers

9000 VAX vax9000 at gmail.com
Tue Nov 8 23:35:00 CST 2005


On 11/8/05, Chuck Guzis <cclist at sydex.com> wrote:
> On 11/8/2005 at 5:36 PM woodelf wrote:
>
> > Well everybody likes 12 bits...
> >  http://www.cray-cyber.org/hardware/Hardware.php
> >   Forget TTL, go tubes!
>
> Wow, now that's ambitious!
>
> Makes me wonder, though.  Around the time the transistor was in its
> ascendancy, the vacuum-tube business came up with a couple of innovations.
> One was the nuvistor--an almost transistor-sized tube; and the other was a
> low-voltage tube used in automobile receivers that were specified for 12.6
> volts on the plate (e.g. 12AE7 dual triode).  These would be coupled with a
> solid-state driver and power amplifier for a auto radio with no vibrator
> supply.
>
>  The first would seem to make the scale of a digital computer more
> attractive; the second would seem to substantially reduce the power
> requirements.    To anyone's knowledge were either of these two components
> ever used in digital applications?

It is funny that I am a tube fan too.

The 12.6 volt tubes won't save you any power; On the contrary, they
sucks much more power than normal tubes. Because they need a lot of
current to heat the cathode to emit more electrons; and they have a
positive first grill to 'pull' electrons out from cathode.

Nuvistors are not good to use for homebrew computers either, because
they are expensive. Months ago I saw a board with 10+ nuvistors. I
didn't buy it ($9.99) because I was not small-tube fan. I checked the
second hand price at that time and it was significantly higher than
those sub $1 tubes.

vax, 9000




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